A rongeur is a robust surgical instrument with a sharp-edged, scoop-shaped tip, used for gouging out bone. A rongeur can be used to open a window in bone, often in the skull. It is used in neurosurgery, podiatric surgery, and orthopedic surgery to expose areas for operation. Other common applications for more specialized types of rongeurs, such as the Kerrison type, include spinal procedures. Common diagnoses for which surgeries involving a rongeur include spinal stenosis, spinal tumors, degenerative disk disease, and herniated disks.
Spinal surgery and neurosurgery typically require the surgeon to remove tissue such as bone and ligament (“target tissue”) to gain access to underlying tissue such as dura, nerve roots, intervertebral disc, spinal cord, and brain (“non-target tissue”) so that the intended surgery can then be performed. As an example, one very common procedure that focuses on discrete elements of the foregoing is a laminectomy in the lumbar, thoracic, or cervical spine, a surgical operation to alleviate a condition known as spinal stenosis. In a laminectomy, a surgeon removes a portion of the vertebrae known as the lamina, usually to give access to the spinal cord or to relieve pressure on nerves. Currently, in the case of highly complex procedures such as a laminectomy, it is common practice for surgeons to employ two sequential methods to achieve removal of target tissue. Generally, a surgeon will first utilize hand-held powered drills or burrs to rapidly remove relatively easily accessible target tissue. Subsequently, because of the risk of potential damage to deeper underlying non-target tissue by a rapidly rotating drill or burr, a manual, unpowered surgical tool known as a rongeur is then applied to remove residual target tissue at a much slower rate. This is done to ensure precise removal of the remaining target tissue, given that the rongeur provides greater precision and control and protection of non-target tissue because of several design features inherent to the conventional rongeur.
The surgery employing the rongeur is performed under constant visualization. Importantly, the component of a conventional rongeur which removes the target tissue is precisely applied via a sliding mechanism, sometimes referred to as a shuttle mechanism, actuated by a trigger or moving handle portion and terminating in a blade or punch mechanism. Additionally, the rongeur includes a protective distal or terminal portion, commonly referred to as a foot plate, that is positioned between target and non-target tissue. This design aspect of a rongeur helps to minimize the chance of damaging non-target tissue.
In using the typical Kerrison-type rongeur, the surgeon must carefully position the rongeur between target and non-target tissue, then squeeze the handle to remove a small piece of target tissue, usually between 2-5 millimeters. Then the entire instrument is withdrawn from the surgical site so the small piece of bone can then be manually removed from the device by the surgeon or the surgeon's assistant. The device then must carefully be reinserted between target and non-target tissue so that the above process can be repeated. Depending on the patient's condition, this process may need to be repeated many times over. In such cases, the surgical procedure is very time-consuming and results in surgical times that can take several hours. The duration of the surgery may lead to substantial bleeding and prolonged administration of general anesthesia that can be detrimental to a patient's recovery. A further downside to the use of such a rongeur is that the repetitive motion may cause hand cramping or fatigue on the part of the surgeon, which increases the risk that a patient may suffer adverse effects from inadvertent tissue removal or from unintended contact of the rongeur's cutting portion with nerve tissue. These and other issues with the traditional design have led to numerous alternative approaches to rongeur design.
Various grasping configurations, cutting or shearing designs, and variations of the two have been proposed to overcome limitations presented by state-of-the-art commercial rongeurs.
Among the designs introduced in recent years to overcome the issue of operator hand fatigue is the Aesculap KAIRison series. This device employs a pneumatic system to obviate much of the need for exerting manual leverage. A significant limitation presented by the design of the device is that it is a Kerrison-type instrument in the form of a bone punch, rather than a smoothly-operating, precisely controlled rotary tool. As in the case of all other Kerrison rongeurs, the retrieval of chipped bone or other tissue detritus is necessary after each section of tissue is ablated or otherwise detached.
Another of the designs proposed to address such concerns are U.S. Pat. No. 8,864,766 to Edgar Weaver, issued Oct. 21, 2014, which presents a Kerrison rongeur employing a bypass-cut type shearing mechanism, for specific cutting and sampling bone, cartilage and soft tissue. One significant limitation of this design is that it will not reliably remove bone or soft tissue with a high degree of precision, due to the broad range of action, or throw, of the cutting elements.
Publication US 20040102783, attributed to Sutterlin et al, discloses a Powered Kerrison-like Rongeur system. The device incorporates a powered cutting element and features a pistol-grip actuator as a design element which appears to be intended to provide an optimized ergonomic effect.
Other inventors have tried to address the issue of debris collection. For example, a number of various commercially available devices for spinal surgery incorporate integral irrigation and suction feature in tissue-removal devices. However, the combination of a powered drill and irrigation or suction mechanisms presently available all feature an inherent limitation, in that the way the irrigation, suction, or combined irrigation-suction mechanisms are attached to the devices in all cases leads to partial obstruction of the surgeon's view of the operative field.
A further limitation present in powered devices is that the operator's ability to select from a range of cutting devices is generally restricted to the limited choice presented by a single manufacturer's pre-determined selection. As such, a surgeon or medical technician must choose from what essentially amounts to a pre-packaged toolkit. No device heretofore has overcome the limitation of the operator not being able to select from a broad range of powered cutting devices which essentially snap into place and may be easily switched out for either another identical cutting tool, or replaced by another brand and design of rotary cutting tool.
As demonstrated by the foregoing, there remains a need for an improved instrument that can cut bone and tissue, such as with a power-driven, longitudinally displaceable or slideable cutting element or burr described herein to avert the problems associated with conventionally designed rongeurs. Such powered elements can include an ability to regulate cutting speed, to actuate the cutting element in such a way as to precisely deploy or retract the burr along a range of motion, and to provide irrigation as needed, thereby reducing operator fatigue and the time of the operative procedure and minimizing the risk of damage to tissue that need not and should not be removed. Additionally, it may be desirable to incorporate an optional irrigation function into such a rongeur. Embodiments of the present device meet these needs by creating a robust, easily sterilized, and highly ergonomic powered medical instrument capable of incorporating any one of a multiplicity of rotary cutting elements of various designs and manufacture, and featuring options such as irrigation, inherent safety features, and presenting the operator with the ability to remove target tissue to a degree and rate heretofore not possible.